1. Field
The present invention relates to a light emitting diode lighting circuit of a saddle-ride-type vehicle such as a motorcycle, and more particularly to a circuit for preventing erroneous lighting of a light emitting diode caused by a leak current or the like from a lighting indicator switch of the light emitting diode.
2. Description of Related Art
As an example of a light emitting diode lighting circuit for preventing erroneous lighting of a light emitting diode, is disclosed in Patent Document 1. As shown in FIG. 1 of Patent Document 1 (Japanese Patent 4039623), the light emitting diode lighting circuit includes a transistor 12 and a differential amplifier 13 which is arranged in front of the transistor 12, a battery 11 is connected to a positive input side of the differential amplifier 13 through a switch 14, a reference resistance Rref is connected to the positive input side, a voltage of the battery 11 is dividedly supplied to a negative input side of the differential amplifier 13 using resistances R1, R2, an ON/OFF of the transistor 12 is controlled corresponding to the voltage difference between positive and negative inputting, and LEDs 9-1 to 9-n are lit in response to turning on of the transistor 12.
The LED used in the light emitting diode lighting circuit is turned on with a minute current and hence, there may be a case where even when a leak current flows at the time of turning off a switch for lighting the LED, the LED is turned on.
According to the above-mentioned configuration of the light emitting diode lighting circuit, values of the respective resistances are set such that the relationship of Rs>(R1/R2)×Rref is established with respect to a leak resistance Rs of the switch 14 and hence, the differential amplifier 13 is not brought into an ON state even when a leak current is generated in the switch 14. Accordingly, also the transistor 12 is not brought into an ON state thus preventing the LEDs 9-1 to 9-n from being lit.
However, in the above-mentioned circuit, the reference resistance Rref is necessary for preventing erroneous lighting caused by a leak current and therefore, there has been a drawback that heat is generated in the reference resistance Rref due to an electric current which flows at the time of generation of a leak current or at the time of turning on the switch 14.